Medico-technical diagnosis appliances such as X-ray computer tomography appliances or magnetic-resonance appliances can be used to produce three-dimensional representations of a tissue being examined, and to process the data. By way of example, it is possible to produce a view path within a three-dimensional model of an object, as is known in principle from U.S. Pat. No. 5,611,025 A. For this purpose, imaging information is segmented or subdivided into individual structures, in which case surface models can be produced from volume data.
In processing of three-dimensional image data, the entire volume under consideration can be subdivided into individual volume elements, also referred to as voxels. In medico-technical imaging methods, each voxel is typically allocated a gray-scale value which indicates physical characteristics, such as absorption characteristics of the tissue being examined. During the evaluation of three-dimensional diagnostic image data, it may be desirable to make only specific types of tissue visible, so that, for example, muscle tissue is displayed in a three-dimensional view, while bones are masked out. In order to select a specific type of tissue for a slice display or for a three-dimensional display from a more extensive data record, it is possible to select from the data record only those voxels whose gray-scale values are within a predetermined interval. However, this does not always allow a clean separation between a type of tissue to be displayed and a type of tissue which is not to be displayed.